The consumption of excessive amounts of edible vegetable oils and animal fats (i.e. triglycerides) has been linked to health problems such as obesity and heart disease. Therefore, there is increasing interest in fat substitutes that can be used as replacements for triglyceride fats in the diet.
Polyol fatty acid polyesters are known for use as fat substitutes in foods. U.S. Pat. No. 3,600,186 to Mattson et al. discloses low calorie, fat-containing, food compositions in which at least a portion of the triglyceride content is replaced with a sugar or sugar alcohol fatty acid ester, the polyester having at least four fatty acid ester groups with each fatty acid having from 8 to 22 carbon atoms. The polyesters are said to be useful in food products such as salad oil, cooking oil, plastic shortening, fried foods, cakes, breads, mayonnaise, margarine, and dairy products.
U.S. Pat. No. 4,005,196 to Jandacek et al. discloses the low calorie fat-containing food compositions of the type disclosed in the Mattson et al. patent, in combination with fat-soluble vitamins selected from the group consisting of vitamin A, vitamin D, vitamin E and vitamin K.
It is known that regular ingestion of moderate to high levels of liquid polyol polyesters can produce an undesirable "oil loss" effect, namely, leakage of the polyesters through the anal sphincter. U.S. Pat. No. 4,005,195 to Jandacek describes a means of preventing the undesirable oil loss effect through the addition to the polyesters of anti-anal leakage agents. The anti-anal leakage agents include solid fatty acids (melting point 37.degree. C. or higher) and their triglyceride source, and solid polyol fatty acid polyesters.
The use of solid triglycerides or solid polyesters as anti-anal leakage agents for liquid polyesters has drawbacks when the polyesters are used in food compositions. A polyester or triglyceride having a solids content high enough to prevent anal leakage, typically tastes waxy in the mouth when ingested. It would be desirable to have a fat substitute that is still an effective substitute for triglyceride fats to make low calorie foods, but that also has a very low solids content so that it does not taste waxy in the mouth. At the same time, it is critical that this fat substitute not produce an undesirable oil-loss side effect.
European Patent Application 0,236,288 to Bernhardt, published Sep. 9, 1987, discloses polyol fatty acid polyesters that are highly resistant to anal leakage even at relatively low levels of solids. This benefit is achieved by polyesters that have a relatively high rheological profile at body temperature. Unfortunately, even the polyol polyesters disclosed by this European Application are not ideal for producing a non-waxy taste impression in foods. Furthermore, the specific polyol polyesters given as examples have poor oxidative stability. The polyesters of the Bernhardt application preferably have a solid fat content at body temperature of at least about 5%, and their viscosity at body temperature is at least about 25 poise at a shear rate of 10 seconds.sup.-1. It would be desirable to have polyol fatty acid polyesters with improved taste impression in combination with oxidative stability.
Oils, such as soybean oil, are often hardened to reduce the degree of polyunsaturation. These hardened oils exhibit improved oxidative stability. One characteristic of typical hardened oils, is a high amount of trans-double bonds in the fatty acid chains. European Patent Application 0,235,836 to Bodor et al., published Sep. 9, 1987, discloses polyol fatty acid polyesters with improved oxidative stability. This benefit is achieved by polyesters that have a relatively high level of trans-unsaturated fatty acid chains.
As the level of trans-double bonds increases, the crystal size of the corresponding partially hardened composition also increases. It has been observed that large crystals correspond to a product with poor liquid-solid stability, i.e. mixtures of the solid and liquid polyesters do not remain homogeneous. This can result in poor anti-anal leakage control. Accordingly, it would be highly desirable to have a polyol polyester composition with a high degree of oxidative stability in combination with a high degree of liquid-solid stability resulting from small crystals.
Therefore, it is an object of the present invention to provide a polyol polyester composition with a low rheological profile which exhibits little or no "oil loss" effect.
It is also an object of the present invention to provide a polyol polyester composition with a high degree of oxidative stability. Accordingly, this composition exhibits a more stable flavor, a more stable color, and a minimal potential for undesirable reactions in the manufacturing process.
It is also an object of the present invention to provide a polyol polyester with a low ratio of solid fat content to liquid/Solid stability.
It is also an object of the present invention to produce a polyol polyester composition with low levels of solids at body temperature to minimize waxiness.
These and other objects of the present invention will become evident from the disclosures herein.